1. Field of the Invention
The present invention relates to an image display apparatus that can execute displaying and erasing operations of images repeatedly by moving display particles in a gaseous phase in response to an electrical field.
2. Description of the Related Art
Conventionally, an image display apparatus that displays images by moving display particles in a gaseous phase has been known. The image display apparatus has a structure in which display particles in a powder state are sealed between two substrates at least one of which is transparent, and by generating an electric field between the substrates, the display particles are moved and adhered to one of the substrates so that an image is displayed. Upon driving such an image display apparatus, a voltage is applied between the substrates to generate an electric field, and the display particles are moved along the electric field direction so that by selecting the electric field direction on demand, displaying and erasing operations of images can be repeatedly executed.
However, once the display particles are adhered to the substrate, the display particles become unmovable in an adhered state to the substrate since the display particles have comparatively high adhesive strength, resulting in a problem such that the contrast between an image portion and a non-image portion deteriorates.
Therefore, a technique has been disclosed in which a substrate surface is treated by using hexamethyl disilazane (International Publication No. WO2004/077140 Pamphlet).
Another technique has been disclosed in which particles having a fine primary particle size are scattered on a substrate surface so that the contact area of the display particles to the substrate is reduced to consequently reduce adhesive strength (JP-A No. 2004-226768).
However, even when any of the above-mentioned techniques are used, it is not possible to obtain a sufficient adhesive-strength-reducing effect, and the problem of contrast is caused. The problem of contrast becomes conspicuous as the displaying operation of image display apparatus is repeatedly carried out.